Mustard Gas

Mustard Gas - Nitrogen Mustard HN and Sulfur Mustard HN are the most feared vesicants, because of their chemical stability, their persistency, their effect on skin as well as eyes and the respiratory tract.

The ease with which sulphur mustard can be manufactured as both a liquid and a vapor would suggest that in a possible future chemical war HD will be preferred to HN. Due to their physical properties, mustards are very persistent in cold and temperate climates. Mustards thickened with other products are very difficult to remove by decontaminating processes.

Within 2 minutes contact time, depending on concentration levels, a drop of mustard on the skin can cause serious damage. Chemical inactivation using chlorination is effective against mustard and lewisite, less so against HN, and is ineffective against phosgene oximine.

WARNING! The eyes are more susceptible to mustard than either the respiratory tract or the skin. The effects of mustard on the eyes are very painful.

Conjunctivitis follows exposure of about 1 hour to concentrations barely perceptible by odor. This exposure does not affect the respiratory tract significantly. A latent period of 4 to 12 hours follows mild exposure, after which there is tearing and a sensation of grit in the eyes. The conjunctiva and the lids become red. Heavy exposure irritates the eyes after 1 to 3 hours and produces severe lesions.

The hallmark of sulphur mustard exposure is a latent symptom and sign-free period of some hours post exposure. The duration of this period and the severity of the lesions are dependent upon the mode of exposure, environmental conditions and individual health. High temperature and wet skin are associated with more severe lesions and shorter latent periods.

If only a small dose is applied to the skin, the skin turns red and itches intensely. At higher doses blister formation starts, generally between 4 and 24 hours after contact, and this blistering can go on for several days before reaching its maximum. The blisters are fragile and usually rupture spontaneously giving way to a suppurating and necrotic wound. The necrosis of the epidermal cells is extended to the underlying tissues, especially to the dermis. The damaged tissues are covered with slough and are extremely susceptible to infection. The regeneration of these tissues is very slow, taking from several weeks to several months.

Mustard attacks all the mucous membranes of the respiratory tract. After a latent period of 4 to 6 hours, it irritates and congests the mucous membranes of the nasal cavity and the throat, as well as the trachea and large bronchi. Symptoms start with burning pain in the throat and hoarseness of the voice. A dry cough gives way to copious expectoration. Airway secretions and fragments of necrotic epitheliums may obstruct the lungs. Damaged lower airways become easily infected, predisposing to pneumonia after approximately 48 hours.

If the inhaled dose has been sufficiently high, the casualty dies in a few days, either from pulmonary edema or mechanical asphyxia due to fragments of necrotic tissue obstructing the trachea or bronchi, or from superimposed bacterial infection, facilitated by an impaired immune response.

The great majority of mustard gas casualties survive. There is no practical drug treatment available for preventing the effects of mustard.

Infection is the most important complicating factor in the healing of mustard burns. There is no consensus on the optimum form of treatment. Protection against these agents can only be achieved by full protective ensemble.

• A respirator protects against eye and lung damage and gives some protection against systemic effects.
• No drug is available for the prevention of the effects of mustard on the skin and mucous membranes. It is possible to protect the skin against very low doses of mustard by covering it with a paste containing a chlorinating agent, e.g., chloramine.
• The only practical protection is physical protection such as the protective respirator and special clothing.